[media] media: v4l2-dev: fix video device index assignment

The side effect of commit 1056e4388b045 ("v4l2-dev: Fix race condition on
__video_register_device") is the increased number of index value assigned
on video_device registration. Before that commit video_devices were
numbered from 0, after it, the indexes starts from 1, because get_index()
always count the device, which is being registered. Some device drivers
rely on video_device index number for internal purposes, i.e. s5p-mfc
driver stopped working after that patch. This patch restores the old method
of numbering the video_device indexes.

Cc: [email protected] # for v3.12
Signed-off-by: Marek Szyprowski <[email protected]>
Acked-by: Sakari Ailus <[email protected]>
Acked-by: Ricardo Ribalda <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index b5aaaac427add9180221b4bd19fe88133e6bc212..0a30dbf3d05c8c1c26086df64ac8382118643d84 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -872,8 +872,8 @@ int __video_register_device(struct video_device *vdev, int type, int nr,
 
        /* Should not happen since we thought this minor was free */
        WARN_ON(video_device[vdev->minor] != NULL);
-       video_device[vdev->minor] = vdev;
        vdev->index = get_index(vdev);
+       video_device[vdev->minor] = vdev;
        mutex_unlock(&videodev_lock);
 
        if (vdev->ioctl_ops)